This invention relates to stepper motors generally, and particularly to the use of such motors in the accurate positioning (placement) of objects such as documents for printing.
In many document transport) and encoding (printing) systems, the document is stepped to successive character positions, and different characters are printed thereon in rapid succession. To ensure accurate placement of the document and rapid printing of the characters, the document must be transported with a minimum amount of time between characters, and the motor must achieve minimum ringing (oscillation) when the document is positioned at a location for printing. Variations in load, and in motors and motor driver circuitry, affect document positioning and linear placement of characters on the document.
Inaccuracies in positioning due to ringing may be introduced at time of manufacture of the transport system, and may not be detected because of lack of adequate calibration. Such inaccuracies also tend to increase with increase in use of the transport system.
What is needed and would be useful therefore is a system which could detect motor oscillations (ringing) either at the time of manufacture of the transport system or during subsequent use of the transport system, and could provide for reduction of such motor oscillations.